This trope refers to a particular sci-fi convention of connoting a "futuristic" setting with doors and hatches that open in unusual, hi-tech ways — doors that dilate like an iris, doors that slide up into the ceiling, doors that dissolve and rematerialize... Apparently, plain old hinges are extinct in the future.

Outside of this wiki, "Dilating door" is science fiction Fan Speak for the more general trope that we call "Cool, but Inefficient". This is a reference to Heinlein's advice that you could evoke a futuristic air by casually throwing out details like "the door dilated", as if such things were nothing to really notice.

Examples:

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Anime & Manga

The doors on the industrial ship in Ghost in the Shell: Innocence don't make any sense. They consists of four squared panels fixed to two hinges on each side of the doorframe at middle height which are tilted sideways and into the walls. However, it looks quite cool when Batou charges through the corridors and every 15 meters one of these opens just a split second before he reaches it.

Films — Live-Action

Alien: The sections of the air duct system on the starship Nostromo are separated by dilating hatches.

Played for Laughs in the film of Barbarella, when Barbarella is wearing (little more than) an animal-skin suit with a long tail and the tail gets trapped in the closing iris.

A bizarre aversion in TRON: Legacy. The interior of Flynn's house in the Grid has obviously visible hinges and door knobs on all of the doors, such that they wouldn't be out of place in a regular modern house. This, of course, is taking place in the entirely virtual world where Cool, but Inefficient is king. Even stranger when compared with the Ascetic Aesthetic design of the rest of the house. In particular, the windows stand out, as they are not made of a solid substance, but instead seem to be Some Kind of Force Field, marking a pretty stark contrast with the doors.

In Star Trek VI: The Undiscovered Country, the Enterprise halls were designed with various decorative pipes along the ceilings. Problem was they often led to walls with doors that opened upward...

Amusingly averted in the 2009 reboot of Star Trek. Whereas the Star Trek universe does other things (see below), the Starfleet facility on Delta Vega has a normal exterior door with a panic bar.

Dr. Who and the Daleks has doors that swing into the sides. However, for some reason, that's just not absurd enough, and one of the doors has to open with a pressure sensor. Said sensor is located three metres away, and elevated by about a foot, meaning that it was utterly useless to the Dalek inhabitants.

James White was fond of this in his Sector General books, even having a speech about what kind of doors there are in the universe. Essentially, doors can open through hinges, slide in or out, open up or down, dilate clockwise or counterclockwise, or create a quantum-physics manipulating field around themselves so that every atom of a person can pass through without hitting the atoms in the door. The person making the speech went on to say that no civilization in the universe was known to be advanced enough to use the last option, and if any were ever to be encountered, "we will be sure to be very polite."

The defensive iris used on the titular gate of Stargate SG-1. Arguably, this can be justified because the alien gate didn't come with a convenient slot to allow sliding a solid metal door over the event horizon. But then they completely forgot to explain where the iris disappears to when open and where the presumably complex mechanism for operating it is. By Stargate Atlantis, they just had a more prop-friendly generally-invisible Force Field to use in case of "Unscheduled Off-World Activation."

Stargate Atlantis: Inside the Wraith Hiveship are organic doors inside folds into the walls automatically when someone comes near them.

The series has far, far too many "dilating doors" to list here, but special mention goes to a door in "Day of the Daleks" which curls up toward the ceiling in a slow, sinister fashion.

"The Ark in Space" also features a sliding door that almost takes the Fourth Doctor's arm off. "I'm rather attached to it," he said.

And, of course, out of universe the classic series TARDIS interior doors qualifies — they were supposed to swing open or closed with the push of a button, but (like many of the show's mechanics) rarely functioned correctly. The new series solved this by doing away with the interior doors entirely.

In Firefly, on Serenity, the doors to the crew quarters were these elaborate swinging ladder/door combination things. Quite space-efficient, if a bit easy to lock from the wrong side. (And not wheelchair-accessible, although the guest quarters were.) Still quite modest for this trope, since all the doors on the ship are opened by hand. The guest quarters have perfectly ordinary, manual sliding doors, again a matter of saving space.

In Mystery Science Theater 3000, the main characters are compelled through an elaborate series of variously opening doors and into the screening room. Well, Cambot is. The audience never sees the other characters during the door sequence; they might be going into the theater through a side door. And this might just be a shout-out to the opening and ending sequences of Get Smart!

The doors to personal quarters on the eponymous Babylon 5 open by rotating clockwise. They have been known to fall on cast members. Others open like modern automatic doors, sliding to either side. Those doors are actually quite clever, as they're held up by electrical power when open and are closed by the Artificial Gravity produced when the station rotates, with no need for a motor to close them. In the event of a hull breach or life-support failure, the doors would slam shut on their own without any active safety system required.

The doors in Descent have a variety of opening animations, from just two panels sliding vertically apart, up to to six-part dilating doors, and several in between.

The Metroid series is an excellent example given that pretty much every door needs to be shot to open. Sometimes they require multiple shots. Sometimes they need missiles.

This is explained in the Metroid Prime games as being a method of bypassing the door's normal opening mechanism; you're basically lowering a weak shield that's there to keep wildlife (or you in the case of stronger ones) out and the doors are opening automatically (presumably there's a more peaceful manner of opening the doors). The ones that need missiles explicitly have a blast shield (which disappears after being removed the first time) on them for extra security. Some areas of Super Metroid have doors which lack the shields and just let your straight through when you approach.

Although GoldenEye (1997) usually does fine with normal sliding doors, the Cavern level features iris doors. And yes, it is a pain in the ass when the door takes 5 seconds to open while you're fighting a horde of 20 enemies in your back...

The Vaults from the Fallout series are sealed behind doors in the form of enormous steel cogwheels that are rolled along a track by a mechanical arm and then slid shut.

Parodied in Fallout 4 in the Mechanist's Lair where the main entrance is a ridiculously complex set of doors that take easily couple of minutes to open entirely. It's also a Shout-Out to Get Smart and/or Mystery Science Theater 3000, being exactly the same as one of the doors in both those series' famous door sequences.

Knights of the Old Republic features a variety of oddly opening doors, ranging from the relatively boring two part doors that slide sideways to ridiculously complex systems of interlocking bars that unlatch and slide apart.

Doors in Doom open upwards, primarily due to limitations of the engine. "Polyobjects" from the version of the engine used in Hexen and later source ports can be used to make doors that actually imitate real-world door behavior.

The BUILD engine used by Duke Nukem 3D and Shadow Warrior allows for a fair variety of doors, including Doom-style vertical ones (including variants which open down or split in the middle), sliding doors, hinged ones (technically just rotating a sector 90 degrees around a pivot sprite), and a couple of more esoteric ones which involve making wall surfaces shrink away to nothing as the door opens (called "Star Trek doors" in the level editor documentation, and a variant which combines that with the aforementioned split vertical door), used for curtains and in alien levels.

Starship Titanic's arboretum has a door that 'grows' open and closed and is made of metal plants.

Dead Space 3 has doors that fold up, rotate and vanish in the alien city.

In PlanetSide 1's Core Combat caverns, the Ancient Vanu facilities all feature large round doors which vanish when approached, then re-materialize. The doors in human facilities such as the bases and towers feature sliding doors which split along the center. Vehicle bay doors in the Tech Plants slide into the ground when a vehicle leaves the vehicle pad.

Some towns in the Pokémon games, especially from Generation 3 and onwards, have either automatic doors for even civilian houses or, in cases like Pokémon Black Version's Opelucid City, thin blue film that fades away into the air (in other words, a diluting door) upon entering, then rematerializes after passing completely through. However, if the setting is old-fashioned, even in more recent games, then the doors are built strictly as hinged boards the way most are in the real world, such as in Sootopolis City (themed on Mykonos, Greece) or White Forest.

The hatch between the Central Control Chamber and the Main Breaker Room is composed of six triangular pieces that can either be inserted and removed straight-on, or rotated into position to provide the standard iris effect. Which method is used appears to be up to the A.I. or computer that happens to be in control at the time.

The doors intended for human use slide into the walls or floor/ceiling just like modern automatic doors. However, the locking mechanisms consists of pieces of one side which will rotate into the other side in full view of everyone. For the test chamber doors, when they're fully locked, the mechanism completes the Portal 2 logo.

In Drowtales, the forest-dwelling light elves make use of a magical version of this trope, formed from living, moving wood that spirals open.

Western Animation

In one episode of Cyberchase, the kids go to Symmetria to find Ava. The building they encounter has a round door with four holes in it, mounted into a wall with four holes in it. By default, the holes don't align, but every once in a while, the door rotates so that they do align briefly. The trick to getting through is to jump through while it's moving. Nobody gets stuck in it, but it's just asking to happen. Good thing those kids are fairly nimble...

In The Legend of Korra, the doors in the police station are a semi-complex pattern of sliding metal slats. Justified, because the main body of the police force are trained Metal Benders, and it's their powers - not mechanisms — that move the doors around. Most of the other doors in the series are traditionally hinged or manually slid doors.

Real Life

Likely inspired by the human eye. The iris is a naturally evolved mechanism for opening and closing, and probably the only biological example of a "door" that doesn't invoke Squick.

Community

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